Preparation of pigments and paints



l example, titanium oxide for use as a pi Patented Aug. 16, '1927.

"ZUNIVT-EDASTATES PATENT OFFICE.

JOSEPH 'nnuumnnn, on nomaon', anemia, ASSIGN'OB TO nnummw mans I CHEMICAL COMPANY, A CORPORATION 01 DELAWARE.

rnnrnnarron or measure AND rnmrs' No Drawing. Application fled April 82,'1928, 8eria1 ll'o. 108,972, and in Great Britain April 22, 1925.

This invention relates to the reparation of paints and pigments, particu arly titanlthe vehicles with which such igments are generally mixed-to form the pamt.

' It has previously been proposed to incorporate zinc oxide or other oxides with, for ent onlaccount of the action of the zinc oxide on the oil with which the pigment is mixed to form a paint, but although certain ad- 'vanta as result therefrom the uality of the I paints adversely aifected by t 'e' lar e proportion of zinc oxide which it is foun necessary to add,-the opacity of the paint being seriously'reduced. I The object of he present invention isthe preparation of a pigment or paint which is free from the aforesaid objections while re- I taining the advantages resultin from the incorporation therein such su stances as the oxides or other salts'of zinc or other compounds which havea simllar actlon.

- I have found that thedesired result as regards action on the oil can be attained with the use of much smaller pro ortions of such substances as zinc oxide, by t e incorporation in the pilgme'nt or paint of metallic peroxides or persa ts. I I Processes are known, however, in which dioxides (erroneously termed peroxides) such as those of leador manganese are incorporated with various pi 'ents but it is to be noted that in this speci cation the term peroxides is to be understood to mean; the true or active peroxides,-that=.-is those substances capable of'producing'h drogen peroxide on treatment with an ad, Similarly the term persalts is to be read as mean ing true persalts which give rise to hydrogenperoxide by'the action of acids.

7 he zinc oxide or the like may even be'dispensed with, if desired, and the pigment made up only (if-the titanium oxide or, other pigmentary substance, for example other rare earth oxygen compounds, having little or no action on linseed oil, together with a' small proportion of metallic vperoxide or persalt. 7 Y The invention accordingly consists in the incorporationw'ith a pigment havin little or no chemical action on linseed oil ut ca-;

ti ne umoxide of bariumperoxide.

pable of forming the opaque body of a paint of an oxidizing a ent containing a metallic peroxideor persa t. a

The invention further consists in the incorporation with a pi ent of the kind'indicated in the pre in paragraph of an oxidizing agent in the orm of a metallic peroxide together with an alkaline substance such; as a metallic oxide, hydroxide or carbonate, for example, ofv zinc, aluminiumor he invention further consists'in the application of the processes indicated in the two preceding paragraphs to pigments containing titanium oxide.

The invention further consists in the incorporation with a paint containing titanium The invention further consists in thei'ncorporation with a pi ment or paint containing titanium oxi e of. a mixture of barium peroxide andzinc oxide, hydroxide or carbonate.

The invention further consists in paints and pigments obtained by the methods herein described and in paints prepared therefrom.

I Experiment shows that titanium oxide itself does not act chemicallyon linseed oil and it. is advanta cops to add to paints prepared with titanium oxide Figments such substances that are capable o acting chemically with the linseed oil. For exam le,.I may add substances acting as oxidizin agents such as the peroxides or persalts o barium or strontium, alone or. with the known alkaline substances such as zinc hydroxide capable ofneutralizing the acid or acids present in the oil or forming therein, In carrying the invention into efiect in one form, taking by way of example a titanium pi ment, the calcined titanium oxide is ground with water and during the inding or subsequently a salt of-zinc in so ution is added and hydroxide of zinc is then precipi -tated by the addition of an alkali. Al-Y ternatively, a zincate in solution may be addedinstead of a zinc salt and the h droxide of zinc precipitated by an acid. T e

hydroxide of zinc prepared by precipitation is preferred as it gives apparently an improved roduct. Instead of zinc hydroxide, zinc car nate may be precipitated by addition of a solu le a1 ali carbonate By the y and added to the pigment either before or division produced by the precipitation in.

the above method. A small proportion of barium peroxide, say 10 per cent, is added to the mixture before or after grindin with the linseed oil or even incorporated with the oil during grinding.

In carrying the invention into effect in another fo-rm, and taking by way of example a titanium pigment, the titanium oxide is mixed with a small proportion of barium peroxide as in the previous case; hydroxide or carbonate of zinc is prepared separately after drying and alternatively'during the grinding with oil or even incorporated with the 011 during the grinding operation. Similar results can be obtained by the incorporation of other metallic hydroxides or carbonates with the titanium pigment and the peroxide or persalt, for example, those of aluminium or magnesium, or other metals, which com ounds have a-similar action. The oxides of these metals prepared in a dry Way and/or calcined may be used.

It is to be noted that the paints prepared in accordance with this invention have been found to withstand the act-ion of atmospheric conditions, and that the aintfilm is of a satisfactory degree of har ness.

It is to be understood that the above-described methods of carrying theinvention into efiect have been given by way of example only as various modifications of the invention may be made without departing from the spirit 'of the invention. For example, a pigment, white or coloured, may consist of oxide of iron, graphite, or other substance having only a very feeble chemical action if any at all on the linseed oil, and the invention is equally applicable thereto.

Having now described myinvention, what I claim as new and desire to secure by Letters Patent is 1. Process for the preparation of a coating material containing a compound of the type of titanium oxide and having covering power,

but little, if any, action on the acids in paint vehicles, comprising adding to said coating materal a metallic oxygen compound capable of liberating hydrogen peroxide by reaction with the acid in said vehicles.

2. Process for the preparation of a coating material containing a titanium oxide pigment, comprising adding thereto a metallic xeaaeae 4. In the process for the preparation of a I coating material containin titanium oxide, the step which comprises din to titanium oxide an oxygen compound 0 one of the metals of the first two groups of the periodic system, said oxygen compound being capable of liberating hydrogen peroxide under the action of acid, and at least one other metallic compound to act as extender.

5. In the process of manufacturing coating material the steps which comprise recipitating a metallic oxygen compound rom solution. into association with an inactive but highly pigmenting metallic oxygen compound, dehydrating the mixture and thereafter adding thereto with mixing a peroxide of one of the metals of the first two groups of the periodic system and apaint vehicle.

6. In the manufacture of coating materials containing titanium oxide pi ments, the steps comprising mixing calcine titanium oxide with water and adding thereto an aqueous zinc solution, treating saidsolution to precipitate therefrom an o 11 compound of zinc into association wit .said titanium oxide, dehydrating the resulting mixture and thereafter adding thereto a small amount of barium peroxide and a paint ve-- hicle.

7. The liquid coating material resulting from the association with a calcined pigmenting oxide and a vehicle, of a metallic oxide compound capable of producing hy-- JOSEPH eLuMENFELi). 

